Multi-ring lens, systems and methods for extended depth of focus

ABSTRACT

Systems and methods for providing enhanced image quality across a wide and extended range of foci encompass vision treatment techniques and ophthalmic lenses such as contact lenses and intraocular lenses (IOLs). Exemplary IOL optics can include an aspheric refractive profile imposed on a first or second lens surface, and a diffractive profile imposed on a first or second lens surface. The aspheric refractive profile can focus light toward a far focus. The diffractive profile can include a central zone that distributes a first percentage of light toward a far focus and a second percentage of light toward an intermediate focus. The diffractive profile can also include a peripheral zone, surrounding the central zone, which distributes a third percentage of light toward the far focus and a fourth percentage of light toward the intermediate focus.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C §119(e) to U.S.Provisional Application No. 61/695,806, filed on Aug. 31, 2012 under thesame title. This application is related to U.S. patent application Ser.No. 12/971,607 filed Dec. 17, 2010, now U.S. Pat. No. 8,480,228, whichissued on Jul. 9, 2013, which claims the benefit of priority to U.S.Provisional Patent Application No. 61/288,255 filed Dec. 18, 2009.Further, this application is related to the following applications whichwere filed Dec. 17, 2010: Single Microstructure Lens, Systems AndMethods, U.S. patent application Ser. No. 12/971,506, now U.S. Pat. No.8,430,508, which issued on Apr. 30, 2013; Ophthalmic Lens, Systems AndMethods With Angular Varying Phase Delay, U.S. patent application Ser.No. 12/971,889, now U.S. Pat. No. 8,444,267, which issued on May 21,2013; and Ophthalmic Lens, Systems And Methods Having At Least OneRotationally Asymmetric Diffractive Structure, U.S. Patent ApplicationNo. 61/424,433. This application is also related to the following U.S.Patent Application No. 61/047,699 and Ser. No. 12/109,251, now U.S. Pat.No. 7,871,162, which issued on Jan. 18, 2011, both filed on Apr. 24,2008; Ser. No. 12/429,155 filed on Apr. 23, 2009, now U.S. Pat. No.8,231,219, which issued on Jul. 31, 2012; Ser. No. 12/372,573 filed onFeb. 17, 2009, now abandoned; Ser. No. 12/197,249 filed on Aug. 23,2008; Ser. No. 12/120,201 filed on Apr. 13, 2008, and Ser. No.12/771,550 filed on Apr. 30, 2010. What is more, this application isrelated to U.S. Pat. Nos. 6,830,332 and 7,896,916. The entire disclosureof each of the above filings is incorporated herein by reference for allpurposes. Full Paris Convention priority is hereby expressly reserved.

BACKGROUND OF THE INVENTION

Embodiments of the present invention relate to vision treatmenttechniques and in particular, to ophthalmic lenses such as, for example,contact lenses, corneal inlays or onlays, or intraocular lenses (IOLs)including, for example, phakic IOLs and piggyback IOLs (i.e. IOLsimplanted in an eye already having an IOL).

Presbyopia is a condition that affects the accommodation properties ofthe eye. As objects move closer to a young, properly functioning eye,the effects of ciliary muscle contraction and zonular relaxation allowthe lens of the eye to change shape, and thus increase its optical powerand ability to focus at near distances. This accommodation can allow theeye to focus and refocus between near and far objects.

Presbyopia normally develops as a person ages, and is associated with anatural progressive loss of accommodation. The presbyopic eye oftenloses the ability to rapidly and easily refocus on objects at varyingdistances. The effects of presbyopia usually become noticeable after theage of 45 years. By the age of 65 years, the crystalline lens has oftenlost almost all elastic properties and has only limited ability tochange shape.

Along with reductions in accommodation of the eye, age may also induceclouding of the lens due to the formation of a cataract. A cataract mayform in the hard central nucleus of the lens, in the softer peripheralcortical portion of the lens, or at the back of the lens. Cataracts canbe treated by the replacement of the cloudy natural lens with anartificial lens. An artificial lens replaces the natural lens in theeye, with the artificial lens often being referred to as an intraocularlens or “IOL”.

Monofocal IOLs are intended to provide vision correction at one distanceonly, usually the far focus. Predicting the most appropriate IOL powerfor implantation has limited accuracy, and an inappropriate IOL powercan leave patients with residual refraction following surgery.Accordingly, it may be necessary for a patient who has received an IOLimplant to also wear spectacles to achieve good far vision. At the veryleast, since a monofocal IOL provides vision treatment at only onedistance and since the typical correction is for far distance,spectacles are usually needed for good near vision and sometimesintermediate vision. The term “near vision” generally corresponds tovision provided when objects are at a distance from the subject eye ofbetween about 1 to 2 feet are substantially in focus on the retina ofthe eye. The term “distant vision” generally corresponds to visionprovided when objects at a distance of at least about 6 feet or greaterare substantially in focus on the retina of the eye. The term“intermediate vision” corresponds to vision provided when objects at adistance of about 2 feet to about 5 feet from the subject eye aresubstantially in focus on the retina of the eye.

There have been various attempts to address limitations associated withmonofocal IOLs. For example, multifocal IOLs have been proposed thatdeliver, in principle, two foci, one near and one far, optionally withsome degree of intermediate focus. Such multifocal or bifocal IOLs areintended to provide good vision at two distances, and include bothrefractive and diffractive multifocal IOLs. In some instances, amultifocal IOL intended to correct vision at two distances may provide anear add power of about 3.0 or 4.0 Diopters.

Multifocal IOLs may, for example, rely on a diffractive optical surfaceto direct portions of the light energy toward differing focal distances,thereby allowing the patient to clearly see both near and far objects.Multifocal ophthalmic lenses (including contact lenses or the like) havealso been proposed for treatment of presbyopia without removal of thenatural crystalline lens. Diffractive optical surfaces, either monofocalor multifocal, may also be configured to provide reduced chromaticaberration.

Diffractive monofocal and multifocal lenses can make use of a materialhaving a given refractive index and a surface curvature which provide arefractive power. Diffractive lenses have a diffractive profile whichconfers the lens with a diffractive power that contributes to theoverall optical power of the lens. The diffractive profile is typicallycharacterized by a number of diffractive zones. When used for ophthalmiclenses these zones are typically annular lens zones, or echelettes,spaced about the optical axis of the lens. Each echelette may be definedby an optical zone, a transition zone between the optical zone and anoptical zone of an adjacent echelette, and an echelette geometry. Theechelette geometry includes an inner and outer diameter and a shape orslope of the optical zone, a height or step height, and a shape of thetransition zone. The surface area or diameter of the echelettes largelydetermines the diffractive power(s) of the lens and the step height ofthe transition between echelettes largely determines the lightdistribution between the different add powers. Together, theseechelettes form a diffractive profile.

A multifocal diffractive profile of the lens may be used to mitigatepresbyopia by providing two or more optical powers; for example, one fornear vision and one for far vision. The lenses may also take the form ofan intraocular lens placed within the capsular bag of the eye, replacingthe original lens, or placed in front of the natural crystalline lens.The lenses may be in the form of a contact lens, most commonly a bifocalcontact lens, or in any other form mentioned herein.

Although multifocal ophthalmic lenses lead to improved quality of visionfor many patients, additional improvements would be beneficial. Forexample, some pseudophakic patients experience undesirable visualeffects (dysphotopsia), e.g. glare or halos. Halos may arise when lightfrom the unused focal image creates an out-of-focus image that issuperimposed on the used focal image. For example, if light from adistant point source is imaged onto the retina by the distant focus of abifocal IOL, the near focus of the IOL will simultaneously superimpose adefocused image on top of the image formed by the distant focus. Thisdefocused image may manifest itself in the form of a ring of lightsurrounding the in-focus image, and is referred to as a halo. Anotherarea of improvement revolves around the typical bifocality of multifocallenses. Since multifocal ophthalmic lenses typically provide for nearand far vision, intermediate vision may be compromised.

A lens with an extended depth of focus may provide certain patients thebenefits of good vision at a range of distances, while having reduced orno dysphotopsia. Various techniques for extending the depth of focus ofan IOL have been proposed. For example, some approaches are based on abulls-eye refractive principle, and involve a central zone with aslightly increased power. Other techniques include an asphere or includerefractive zones with different refractive zonal powers.

Although certain proposed treatments may provide some benefit topatients in need thereof, still further advances would be desirable. Forexample, it would be desirable to provide improved IOL systems andmethods that confer enhanced image quality across a wide and extendedrange of foci without dysphotopsia. Embodiments of the present inventionprovide solutions that address the problems described above, and henceprovide answers to at least some of these outstanding needs.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention generally provide improved lensesand imaging techniques. Exemplary embodiments provide improvedophthalmic lenses (such as, for example, contact lenses, corneal inlaysor onlays, or intraocular lenses (IOLs) including, for example, phakicIOLs and piggyback IOLs) and associated methods for their design anduse.

Embodiments of the present invention encompass IOL optics having acircular surface structure with one to four echelettes surrounding thesurface structure. The profile is designed such that it increases thedepth of focus of the pseudophakic eye, where the natural crystallinelens of the eye is substituted with a synthetic lens. Such limited ringIOL techniques suppress the distinct bifocality associated withtraditional multifocal IOLs which have many diffractive rings.Consequently, dysphotopsia (e.g., halo effects) associated withtraditional multifocal IOLs can be alleviated by lenses according toembodiments of the present invention.

An exemplary limited ring IOL includes an anterior face and a posteriorface. A profile can be imposed on the anterior or posterior surface orface. The profile can have an inner portion and an outer portion. Theinner portion typically presents a parabolic curved shape. The innerportion may also be referred to as a microstructure, or a central orinner echelette. Between the inner portion and the outer portion, theremay be a transition zone that connects the inner and outer portions. Theouter portion may be comprised of four or fewer echelettes.

In addition to parabolic shapes, the central/inner echelette can haveany of a variety of shapes including hyperbolic, spherical, aspheric,and sinusoidal. The transition between the inner and outer portions ofthe central/inner echelette can be a sharp transition, or it can be asmooth transition.

The surface of the outer portion at the outside of the microstructurecan have any spherical or aspherical shape and is comprised of a limitednumber of echelettes, preferably less than four. The shape of the outerportion can be optimized for having the desired optical performance fora range of pupil sizes. The desired optical performance can be based onelements such as the depth of focus, the optical quality in the farfocus, and the change in best focus (or far focus) position as afunction of the pupil size. Optimization rules may be applied as if theshape were a refractive monofocal IOL, or a refractive IOL having anextended depth of focus, or a refractive design that corrects ormodifies the ocular spherical aberration. Specific designs can be madein which the interplay between the central echelette and the outer zoneis incorporated in the design or optimization. The techniques describedherein are well suited for implementation with any of a variety ofophthalmic lenses, including IOLs, corneal inlays or onlays, and/orcontact lenses.

In one aspect, embodiments of the present invention encompass ophthalmiclens systems and methods for treating an eye of a patient. An exemplarylens may include an anterior face with an anterior refractive profileand a posterior face with a posterior refractive profile. The faces maybe disposed about an optical axis. The lens may also include adiffractive profile imposed on the anterior refractive profile or theposterior refractive profile. In some cases, the diffractive profile mayinclude no more than 5 echelettes. Optionally, the central echelette canbe disposed within a central zone of the lens. Relatedly, the centralechelette may be disposed within an annular ring surrounding a centralrefractive zone of the lens. In some cases, the lens includes aperipheral zone with a limited number of echelettes that surround thecentral echelette or annular ring. The limited number of echelettes maybe characterized by a constant phase shift.

According to some embodiments, an ophthalmic lens can include a limitednumber of echelettes that are characterized by parabolic curves. Thecentral echelette can have a diameter within a range from about 1 mm toabout 4 mm. For example, the central echelette may have a diameter ofabout 1.5 mm. In some cases, the central echelette can have a diameterwithin a range from about 1.0 mm to about 5.0 mm. Lens embodiments mayinclude a peripheral portion comprised of a limited number of echelettesand a refractive portion. Central and peripheral echelettes can have asurface area that is between 1 and 7 mm². For example, the echelettesmay have a surface area that is 2.3 mm². In some cases, a lens mayinclude a peripheral portion which surrounds the echelettes. A lens mayinclude a peripheral portion having an outer diameter within a rangefrom about 4 mm to about 6 mm. In some cases, the peripheral portionwill have an outer diameter within a range of about 1 mm to about 7 mm.For example, a lens may include a peripheral portion having an outerdiameter of about 5 mm.

The echelettes may be characterized by a step height having a valuewithin a range from about 0.5 μm and about 4 μm. According to someembodiments, a transition can be characterized by a step height having avalue within a range of about 1.5 μm and 2.5 μm. According to someembodiments, a transition can be characterized by a step height having avalue of about 1.7 μm. In other embodiments, the step height may have avalue of about 2.0 μm.

Optionally, a diffractive profile can be characterized by a designwavelength, and a lens can include a transition characterized by a stepheight producing a phase shift between about 0.25 and about 1 times thedesign wavelength. In some cases, a diffractive profile can becharacterized by a design wavelength, and the lens can include atransition characterized by a step height producing a phase shiftbetween about 0.15 and about 2 times the design wavelength.

In some aspects, embodiments of the present invention encompass systemsand methods involving an ophthalmic lens that include an anterior facewith an anterior refractive profile and a posterior face with aposterior refractive profile, such that the faces are disposed about anoptical axis, and a diffractive profile imposed on the anteriorrefractive profile or the posterior refractive profile, such that thediffractive profile includes an inner echelette and four or fewer outerechelettes. According to some embodiments, an inner echelette can bedisposed within a central zone of the lens. In some cases, an innerechelette can be disposed within an annular ring surrounding a centralzone of the lens. Optionally, an inner echelette and outer echelettescan be characterized by a parabolic curve. In some cases, an innerechelette and outer echelettes can be characterized by a constant phaseshift. According to some embodiments, an ophthalmic lens may include anaccommodating lens and/or a multifocal lens.

In one aspect, embodiments of the present invention encompass ophthalmiclenses, and systems and methods for their design and fabrication.Exemplary ophthalmic lenses may include a first surface and a secondsurface, where the first and second surfaces are disposed about anoptical axis, an aspheric refractive profile imposed on the first orsecond surface, and a diffractive profile imposed on the first or secondsurface. The aspheric refractive profile can focus or direct lighttoward a far focus. The diffractive profile may include a central zonethat distributes a first percentage of light toward a far focus and asecond percentage of light toward an intermediate focus, and aperipheral zone, surrounding the central zone, that distributes a thirdpercentage of light toward the far focus and a fourth percentage oflight toward the intermediate focus. In some instances, the intermediatefocus corresponds to an intraocular add power within a range between 1Diopter and 2.5 Diopters. In some instances, the intermediate focuscorresponds to an add power between 0.75 and 2 Diopters in the spectacleplane. In some instances, the intermediate focus corresponds to anintraocular add power of 1.75 Diopters. According to some embodiments,the far focus corresponds to a first diffractive order of thediffractive profile. In some cases, the far focus corresponds to asecond diffractive order of the diffractive profile. In some cases, thefar focus corresponds to a third diffractive order of the diffractiveprofile. In some cases, a difference between the intermediate focus andthe far field focus corresponds to a power value within a range fromabout 1 Diopter to about 2.5 Diopters. Optionally, a difference betweenthe intermediate focus and the far field focus may correspond to a powerof about 1.75 Diopters. According to some embodiments, the central zonehas an outer diameter within a range from about 1 mm to about 3 mm.According to some embodiments, the central zone has an outer diameter ofabout 2.2 mm. In some instances, the percentage of light distributed bythe central zone toward the far focus is within a range between 41% and63%, and the percentage of light distributed by the central zone towardthe intermediate focus is within a range between 21% and 41%. In someinstances, the percentage of light distributed by the central zonetoward the far focus is 41% and the percentage of light distributed bythe central zone toward the intermediate focus 41%. In some instances,the percentage of light distributed by the peripheral zone toward thefar focus is within a range between 41% and 100% and the percentage oflight distributed by the peripheral zone toward the intermediate focusis within a range from 0% to 41%. In some instances, the percentage oflight distributed by the peripheral zone toward the far focus is 63% andthe percentage of light distributed by the peripheral zone toward theintermediate focus is 21%. Optionally, the central zone may include oneor more echelettes each having a step height, and the peripheral zonemay include a plurality of echelettes each having a step height that isless than the step height of each central zone echelette. In someinstances, the central zone includes two or more echelettes. Optionally,the central zone may include three or more echelettes. In someinstances, the central zone may include two, three, four echelettes.According to some embodiments, the central zone includes at least oneechelette having a step height of about 0.006 millimeters, and theperipheral zone includes at least one echelette having a step height ofabout 0.0055 millimeters. In some instances, the central zone includesat least one echelette having an optical path difference of 1.5wavelengths, and the peripheral zone includes at least one echelettehaving an optical path difference of 1.366 wavelengths. In someinstances, the central zone includes two echelettes each having a stepheight, and the peripheral zone includes seven echelettes each having astep height less than the step heights of the central zone echelettes.In some instances, the central zone includes an inner echelette havingan outer diameter of 1.6 mm and an outer echelette having an outerdiameter of 2.2 mm, where the inner and outer echelettes of the centralzone each have a step height, and the peripheral zone includes sevenechelettes each having a step height less than the step heights of thecentral zone echelettes. For an add power range of 1.0-2.5 Diopters,there may be one to five echelettes in the central zone and three totwenty four echelettes in the peripheral zone. For an add power range of0.75-2.0 Diopters, there may be one to four echelettes in the centralzone and three to nineteen echelettes in the peripheral zone. In someinstances, the peripheral zone may have in the range of five to twelveechelettes. Optionally, the lens may provide an MTF at 50 c/mm of 24 atthe intermediate focus and an MTF at 50 c/mm of 44 at the far focus.

In another aspect, embodiments of the present invention encompassophthalmic lenses that include means for compensating for ocularspherical aberration, means for compensating for ocular chromaticaberration, and means for providing an extended depth of focus. In someinstances, the means for providing an extended depth of focus includes alens surface having a diffractive profile. In some instances, the meansfor providing an extended depth of focus includes a lens surface havinga refractive profile. In some instances, the means for providing anextended depth of focus includes a lens surface having a diffractive anda refractive profile. In some instances, the means for providing anextended depth of focus includes a lens surface having a profile that isneither diffractive nor refractive.

In another aspect, embodiments of the present invention encompassophthalmic lenses that include means for compensating for ocularspherical aberration, and means for compensating for ocular chromaticaberration. The means for compensating for ocular chromatic aberrationand the means for compensating for ocular spherical aberration whencombined can provide a far focus corresponding to a base power and anintermediate focus corresponding to an add power, and a differencebetween the base power and the add power can define an extended depth offocus for the lens. In some instances, the base power is within a rangefrom 5 to 34 Diopters and the add power is within a range from 1 to 2.5Diopters. In some instances, the means for compensating for ocularspherical aberration includes a lens surface having an asphericalprofile. In some instances, the means for compensating for ocularchromatic aberration includes a lens surface having a diffractiveprofile. In some instances, the means for compensating for ocularchromatic aberration includes a lens material construction, theconstruction having a first material providing a first opticaldispersion and a second material providing a second optical dispersiondifferent from the first optical dispersion.

In still another aspect, embodiments of the present invention encompassophthalmic lenses that include means for compensating for cornealspherical aberration, means for compensating for ocular chromaticaberration, and means for providing an extended depth of focus. In someinstances, the means for providing an extended depth of focus includes alens surface having a diffractive profile. In some instances, the meansfor providing an extended depth of focus includes a lens surface havinga refractive profile. In some instances, the means for providing anextended depth of focus includes a lens surface having a diffractive anda refractive profile. In some instances, the means for providing anextended depth of focus includes a lens surface having a profile that isneither diffractive nor refractive.

In yet another aspect, embodiments of the present invention encompassophthalmic lenses that include means for compensating for cornealspherical aberration, and means for compensating for ocular chromaticaberration. The means for compensating for ocular chromatic aberrationand the means for compensating for ocular spherical aberration whencombined can provide a modulation transfer function value at 50 cyclesper millimeter of at least 10, for an intermediate focus, at 3 mm and 5mm pupil diameters. In some cases, the means for compensating forcorneal spherical aberration includes a lens surface having anaspherical profile. In some cases, the means for compensating for ocularchromatic aberration includes a lens surface having a diffractiveprofile. In some cases, the diffractive profile includes a central zonethat distributes a first percentage of light toward a far focus and asecond percentage of light toward the intermediate focus, and aperipheral zone, surrounding the central zone, that distributes a thirdpercentage of light toward the far focus and a fourth percentage oflight toward the intermediate focus. In some cases, the means forcompensating for ocular chromatic aberration includes a lens materialconstruction, the construction having a first material providing a firstoptical dispersion and a second material providing a second opticaldispersion different from the first optical dispersion.

In yet another aspect, embodiments of the present invention encompassmethods for generating an ophthalmic lens prescription for a patient.Exemplary methods may include inputting a patient parameter data profilespecific for the patient, where the patient parameter data profileincludes a patient spherical aberration parameter corresponding to ameasured spherical aberration of the patient and a patient chromaticaberration parameter corresponding to a measured chromatic aberration ofthe patient. Methods may also include generating the ophthalmic lensprescription for the patient. The ophthalmic lens prescription can beconfigured to compensate for the measured patient spherical aberrationand the measured patient chromatic aberration and to provide a far focuscorresponding to a base power and an intermediate focus corresponding toan add power, where a difference between the base power and the addpower defines an extended depth of focus for the ophthalmic lens. Insome instances, the ophthalmic lens prescription may include a contactlens prescription, a phakic intraocular lens prescription, apseudophakic intraocular lens prescription, or a corneal inlayprescription. In some instances, the patient spherical aberrationparameter includes an ocular spherical aberration parameter. In someinstances, the patient spherical aberration parameter includes a cornealspherical aberration parameter. In some instances, the patient chromaticaberration parameter includes an ocular chromatic aberration parameter.In some instances, the patient chromatic aberration parameter includes acorneal chromatic aberration parameter.

In still yet another aspect, embodiments of the present inventionencompass methods for fabricating an ophthalmic lens prescription for apatient. Exemplary methods may include inputting an ophthalmic lensprescription for a patient, and fabricating the ophthalmic lens based onthe prescription. In some cases, the ophthalmic lens is configured tocompensate for a patient spherical aberration and a patient chromaticaberration, and the lens is configured to provide a far focuscorresponding to a base power and an intermediate focus corresponding toan add power, where a difference between the base power and the addpower defines an extended depth of focus for the ophthalmic lens. Insome cases, the ophthalmic lens is a contact lens, a phakic intraocularlens, a pseudophakic intraocular lens, or a corneal inlay.

In another aspect, embodiments of the present invention encompasssystems for generating an ophthalmic lens prescription for an eye of apatient. Exemplary systems may include an input that accepts a patientparameter data profile specific for the patient eye, where the patientparameter data profile includes a patient spherical aberration parametercorresponding to a measured spherical aberration of the patient eye anda patient chromatic aberration parameter corresponding to a measuredchromatic aberration of the patient eye. Systems may also include amodule having a tangible medium embodying machine-readable code thatgenerates the ophthalmic lens prescription for the eye. The ophthalmiclens prescription can be configured to compensate for the measuredspherical and chromatic aberrations and to provide a far focuscorresponding to a base power and an intermediate focus corresponding toan add power, where a difference between the base power and the addpower defines an extended depth of focus for the ophthalmic lens.

In one aspect, embodiments of the present invention encompass systemsfor fabricating an ophthalmic lens for an eye of a patient. Exemplarysystems may include an input that accepts an ophthalmic lensprescription for the patient eye, where the ophthalmic lens prescriptionis configured to compensate for a measured patient spherical aberrationand a measured patient chromatic aberration of the patient eye, and toprovide a far focus corresponding to a base power and an intermediatefocus corresponding to an add power. A difference between the base powerand the add power can define an extended depth of focus for theophthalmic lens prescription. Systems may also include a manufacturingassembly that fabricates the ophthalmic lens based on the lensprescription.

For further understanding of the nature and advantages of the presentinvention, reference should be made to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view of an eye with a multifocal refractiveintraocular lens.

FIG. 1B is a cross-sectional view of an eye having an implantedmultifocal diffractive intraocular lens.

FIG. 2A is a front view of a diffractive multifocal ophthalmic lens.

FIG. 2B is a cross-sectional view of the lens of FIG. 2A.

FIGS. 3A-3B are a graphical representations of a portion of thediffractive profile of a conventional diffractive multifocal lens.

FIG. 4 shows aspects of the central echelette of a lens according toembodiments of the present invention.

FIG. 4A-4E illustrates aspects of a lens profile according toembodiments of the present invention.

FIG. 5 shows aspects of calculated defocus curves according to a centralechelette embodiment.

FIG. 6 shows aspects of calculated defocus curves according to aembodiments of the present invention.

FIGS. 7 and 7-1 depict aspects of ophthalmic lenses according toembodiments of the present invention.

FIGS. 8, 8-1, and 8A to 8E depict aspects of ophthalmic lenses accordingto embodiments of the present invention.

FIGS. 9A and 9B depict aspects of ophthalmic lenses according toembodiments of the present invention.

FIGS. 10A and 10B depict aspects of ophthalmic lenses according toembodiments of the present invention.

FIGS. 11A and 11B depict aspects of ophthalmic lenses according toembodiments of the present invention.

FIGS. 12A and 12B depict aspects of ophthalmic lenses according toembodiments of the present invention.

FIG. 13 depicts aspects of ophthalmic lens prescription generationmethods according to embodiments of the present invention.

FIG. 14 depicts aspects of ophthalmic lens fabrication methods accordingto embodiments of the present invention.

FIG. 15 depicts aspects of ophthalmic lens prescription generationsystems according to embodiments of the present invention.

FIG. 16 depicts aspects of ophthalmic lens fabrication systems accordingto embodiments of the present invention.

For illustration purposes, the profile geometries shown in certainaforementioned figures were not drawn exactly to scale. The heights ofthe profiles shown in some of the figures are generally on the order ofabout 0.1 μm to about 8.0 μm although the heights may vary depending onfactors such as the amount of correction needed by the patient, therefractive index of the lens material and surrounding medium, and thedesired distribution of light between wanted diffraction orders.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the figures and descriptions of the presentinvention have been simplified to illustrate elements that are relevantfor a clear understanding of the present invention, while eliminating,for the purpose of clarity and brevity, many other elements found intypical ophthalmic lenses, implantable optic apparatuses, systems andmethods. Those of ordinary skill in the art may thus recognize thatother elements and/or steps are desirable and/or required inimplementing the present invention. However, because such elements andsteps are well known in the art, and because they do not facilitate abetter understanding of the present invention, a discussion of suchelements and steps is not provided herein. The disclosure herein isdirected to all such variations and modifications to the disclosedelements and methods known to those skilled in the art.

Embodiments of the present invention encompass systems and methods thatprovide improved image quality over an extended range of focal points orfoci. Systems and methods disclosed herein can encompass variousophthalmic lenses such as, for example, contact lenses, intraocularlenses, spectacle lenses, and corneal inlays or onlays. Exemplaryembodiments include ophthalmic lenses having an extended depth of focus,as compared to conventional monofocal lenses, and reduced dysphtopsia ascompared to conventional multifocal ophthalmic lenses. In some cases,such techniques involve an IOL approach that includes a limited numberof rings or echelettes, and typically involves an expanded depth offocus. Advantageously, such approaches can provide a patient with gooddistance vision, as well as good vision at intermediate and/or neardistances without dysphotopsia.

Embodiments of the present invention generally provide improved lensesand imaging systems and may be incorporated into any system in which alens with an extended depth of focus may be advantageous, such ascamera/video lenses, including those used for surveillance or forsurgical procedures, as well as for cameras in mobile phones or otherrelated devices. Embodiments of the invention may find their mostimmediate use in the form of improved ophthalmic devices, systems, andmethods. Exemplary embodiments of the present invention provide improvedophthalmic lenses (including, for example contact lenses, intraocularlenses (IOLs), corneal implants and the like) and associated methods fortheir design and use. Embodiments of the present invention may be usedwith monofocal diffractive or refractive lenses, bifocal diffractive orrefractive lenses, and multifocal diffractive or refractive lenses, e.g.embodiments of the present invention could be added to the oppositesurface of multifocal IOLs. In other words, an extended depth of focusfeature may be added to, for example the opposite surface of adiffractive or refractive multifocal embodiment.

In addition, an extended depth of focus feature may be added to, forexample, a toric IOL, an IOL that modifies ocular spherical and/orchromatic aberration, and/or an accommodating IOL. In general, anextended depth of focus feature may be added to an IOL that modifiesocular aberrations.

Reading is often done in bright light conditions in which the pupil issmall. In contrast, night-time driving is done in low light conditionsin which the pupil is large. Embodiments of the present inventionencompass lenses that relatively emphasize intermediate or near visionfor small pupil sizes, while also relatively emphasizing far vision forlarge pupil sizes. In some such ophthalmic lenses, a greater proportionof light energy may be transmitted to the far focus from a peripheralportion of the lens to accommodate for low light, far viewing conditionssuch as night time driving, with the near or intermediate viewingreceiving relatively more light energy from a central portion of thediffractive profile—for reading or computer work for example and/or toprovide depth of focus and intermediate or near viewing under low lightreading conditions as in for example reading restaurant menus.

FIG. 1A is a cross-sectional view of an eye E fit with a multifocal IOL11. As shown, multifocal IOL 11 may, for example, comprise a bifocalIOL. Multifocal IOL 11 receives light from at least a portion of cornea12 at the front of eye E and is generally centered about the opticalaxis of eye E. For ease of reference and clarity, FIGS. 1A and 1B do notdisclose the refractive properties of other parts of the eye, such asthe corneal surfaces. Only the refractive and/or diffractive propertiesof the multifocal IOL 11 are illustrated.

Each major face of lens 11, including the anterior (front) surface andposterior (back) surface, generally has a refractive profile, e.g.biconvex, plano-convex, plano-concave, meniscus, etc. The two surfacestogether, in relation to the properties of the surrounding aqueoushumor, cornea, and other optical components of the overall opticalsystem, define the effects of the lens 11 on the imaging performance byeye E. Conventional, monofocal IOLs have a refractive power based on therefractive index of the material from which the lens is made, and alsoon the curvature or shape of the front and rear surfaces or faces of thelens.

In a young, healthy eye contraction and relaxation of ciliary muscles 17surrounding the capsular bag 14 contribute to accommodation of the eye,the process by which the eye increases optical power to maintain focuson objects as they move closer. As a person ages, the degree ofaccommodation decreases and presbyopia, the diminished ability to focuson near objects, often results. A patient may therefore conventionallyuse corrective optics having two optical powers, one for near vision andone for far vision, as provided by multifocal IOL 11.

Multifocal lenses may optionally also make special use of the refractiveproperties of the lens. Such lenses generally include different powersin different regions of the lens so as to mitigate the effects ofpresbyopia. For example, as shown in FIG. 1A, a perimeter region ofrefractive multifocal lens 11 may have a power which is suitable forviewing at far viewing distances. The same refractive multifocal lens 11may also include an inner region having a higher surface curvature and agenerally higher overall power (sometimes referred to as a positive addpower) suitable for viewing at near distances.

Rather than relying entirely on the refractive properties of the lens,multifocal diffractive IOLs or contact lenses can also have adiffractive power, as illustrated by the IOL 18 shown in FIG. 1B. Thediffractive power can, for example, comprise positive or negative addpower, and that add power may be a significant (or even the primary)contributor to the overall optical power of the lens. The diffractivepower is conferred by a plurality of concentric diffractive zones whichform a diffractive profile. The diffractive profile may either beimposed on the anterior face or posterior face or both.

The diffractive profile of a diffractive multifocal lens directsincoming light into a number of diffraction orders. As light 13 entersfrom the front of the eye, the multifocal lens 18 directs light 13 toform a far field focus 15 a on retina 16 for viewing distant objects anda near field focus 15 b for viewing objects close to the eye. Dependingon the distance from the source of light 13, the focus on retina 16 maybe the near field focus 15 b instead. Typically, far field focus 15 a isassociated with 0^(th) diffractive order and near field focus 15 b isassociated with the 1^(st) diffractive order, although other orders maybe used as well.

Multifocal ophthalmic lens 18 typically distributes the majority oflight energy into the two viewing orders, often with the goal ofsplitting imaging light energy about evenly (50%:50%), one viewing ordercorresponding to far vision and one viewing order corresponding to nearvision, although typically, some fraction goes to non-viewing orders.

In some embodiments, corrective optics may be provided by phakic IOLs,which can be used to treat patients while leaving the natural lens inplace. Phakic IOLs may be angle supported, iris supported, or sulcussupported. The phakic IOL can be placed over the natural crystallinelens or piggy-backed over another IOL. It is also envisioned that thepresent invention may be applied to inlays, onlays, accommodating IOLs,spectacles, and even laser vision correction.

FIGS. 2A and 2B show aspects of a standard diffractive multifocal lens20. Multifocal lens 20 may have certain optical properties that aregenerally similar to those of multifocal IOLs 11, 18 described above.Multifocal lens 20 has an anterior lens face 21 and a posterior lensface 22 disposed about optical axis 24. The faces 21, 22 of lens 20typically define a clear aperture 25. As used herein, the term “clearaperture” means the opening of a lens or optic that restricts the extentof a bundle of light rays from a distant source that can be imaged orfocused by the lens or optic. The clear aperture is usually circular andis specified by its diameter, and is sometimes equal to the fulldiameter of the optic.

When fitted onto the eye of a subject or patient, the optical axis oflens 20 is generally aligned with the optical axis of eye E. Thecurvature of lens 20 gives lens 20 an anterior refractive profile and aposterior refractive profile. Although a diffractive profile may also beimposed on either anterior face 21 and posterior face 22 or both, FIG.2B shows posterior face 22 with a diffractive profile. The diffractiveprofile is characterized by a plurality of annular optical zones orechelettes 23 spaced about optical axis 24. While analytical opticstheory generally assumes an infinite number of echelettes, a standardmultifocal diffractive IOL typically has at least 9 echelettes, and mayhave over 30 echelettes. For the sake of clarity, FIG. 2B shows only 4echelettes. Typically, an IOL is biconvex, or possibly plano-convex, orconvex-concave, although an IOL could be plano-plano, or otherrefractive surface combinations.

FIGS. 3A and 3B are graphical representations of a portion of a typicaldiffractive profile of a multifocal lens. While the graph shows only 3full echelettes, typical diffractive lenses extend to at least 9echelettes to over 32 echelettes. In FIG. 3A, the height of the surfacerelief profile (from a plane perpendicular to the light rays) of eachpoint on the echelette surface is plotted against the square of theradial distance (r² or ρ) from the optical axis of the lens. Inmultifocal lenses, each echelette 23 may have a diameter or distancefrom the optical axis which is often proportional to √n, n being thenumber of the echelette 23 as counted from optical axis 24. Eachechelette has a characteristic optical zone 30 and transition zone 31.Optical zone 30 has a shape or downward slope that may be linear whenplotted against p as shown in FIG. 3A. When plotted against radius r,optical zone 30 has a shape or downward slope that is parabolic as shownin FIG. 3B. As for the typical diffractive multifocal lens, as shownhere, all echelettes have the same surface area. The area of echelettes23 determines the add power of lens 20, and, as area and radii arecorrelated, the add power is also related to the radii of theechelettes.

As shown in FIGS. 3A and 3B, transition zone 31 between adjacentechelettes is sharp and discontinuous. The height of the lens facesharply transitions from sloping steadily downwards to steppingvertically upwards, and the transitions abruptly back to slopingsteadily downwards again. In doing so, echelettes 23 also have acharacteristic step height 32 defined by the distance between the lowestpoint and height point of the echelette. Hence, the slope (or firstderivative) and/or the curvature (second derivative) of the diffractivesurface are discontinuous adjacent the transitions.

Structure of Central Echelette

FIG. 4 provides a graphical representation of a cross section of aportion of an exemplary lens illustrating the central echelettestructure. The lens profile 200 has a ring diameter of 1.21 mm and astep height at 220 of 2.05 μm, corresponding with a phase delay of 0.5lambda (see table 2). In this example, the ring diameter was reducedfrom 1.5 mm (which is the inner ring diameter for a 2.0 Diopterconventional IOL diffractive lens) to 1.21 mm by a scaling factor √2, asdescribed in U.S. Pat. No. 5,121,980 (Cohen). Only the inner portion andpart of the outer portion of half of the lens is shown, although sincethe lens is rotationally symmetric, the other half is a mirror image.

The adjacent echelette(s) in the outer portion (not shown) are detailedbelow. Profile 200 includes an inner portion 210 or single ring, a stepor transition 220, and an outer portion 230. The outer portion 230extends beyond that disclosed in FIG. 4F to 2.5 mm and may be comprisedof limited additional echelettes. Inner portion 210 extends between acentral location 210 of profile 200 and transition 220. Outer portion230 extends between transition 220 and a peripheral location (notshown). In some cases, transition 220 can be disposed at a distance fromthe optical axis that is within a range from about 0.5 mm to about 2.0mm, and peripheral location can be disposed at a distance from theoptical axis that is within a range from about 2.0 to about 3.5 mm, orbigger (for example, for contact lenses, the ranges would beapproximately 15% larger due to the optically more powerful position ofcontact lens compared to an IOL; those skilled in the art wouldappropriately scale certain dimensions depending on the application).

The inner portion or echelette 210 includes a center 210 a and aperipheral edge 210 b. At center or central section 210 a of innerportion 210 where radial distance is zero, the sag (d) of inner portionis between the sag (d) of the diffractive base curve 240 and the sag (d)of the peripheral curve 260 at 1.03 μm from the peripheral curve 260,corresponding with a phase delay of 0.25 lambda (see table 2). Atperipheral edge 210 b, the sag (d) of inner portion 210 is substantiallyequivalent to the sag (d) of diffractive base curve 240 at 13.8 μm. Thevalue of sag (d) between radial distance zero and radial distance at theperipheral edge 210 b at 0.61 mm, gradually and smoothly changes from1.03 μm (at r=0) to the value of the base curve 240 (at r=0.61 mm) whichis 13.8 μm. This change occurs in a parabolic fashion. As shown here,inner portion can present a parabolic shape, for example as described inEquation 4a of Cohen, Applied Optics, 31:19, pp. 3750-3754 (1992),incorporated herein by reference.

At the peripheral edge 210 b where the radial distance (r) is 0.61 mm,the value of sag (d) steps or changes from the value of diffractive basecurve 240 to the value of peripheral curve 260. Where radial distance(r) corresponds to transition 220, sag (d) of inner portion isequivalent to the value of the diffractive base curve 240. Relatedly,the displacement of the profile approaches that of the diffractive basecurve as the radial distance increases from a value of zero to a valueof about 0.61 mm. The step height is 2.05 μm resulting in a phase delayof 0.5.

The outer portion 230 includes an inner or central edge 230 a and aperipheral edge (not shown). At inner edge 230 a, the sag (d) of outerportion is substantially equivalent to the sag (d) of peripheral curve260. At peripheral edge, the sag (d) of outer portion remainssubstantially equivalent to the sag (d) of peripheral curve 260. Asdetailed below, a limited number of echelettes may be located betweeninner edge 230 a and peripheral edge.

FIG. 4A provides a graphical representation of a portion of a lensdiffractive profile with a central echelette and one peripheral adjacentechelette according to embodiments of the present invention. In FIG. 4A,the height of the surface relief profile (from a plane perpendicular tothe light rays) of each point on the echelettes surface is plottedagainst the distance from the optical axis of the lens. The echelettescan have a characteristic optical zone 930 and transition zone 931.Optical zone 930 can have a shape or downward slope that may be linearwhen plotted against p as shown in FIG. 4A. When plotted against radiusr, optical zone 930 can have a shape or downward slope that isparabolic. Central and peripheral echelettes can have a surface areathat is between 1 and 7 mm². For example, the echelettes may have asurface area that is 2.3 mm². An outer (refractive) zone can follow thebase radius with a fixed offset.

As shown in FIG. 4A, transition zones 931 between the optical zones 930and the adjacent optical zones can be sharp and discontinuous.Similarly, a vertical transition between adjacent echelettes and alsothe peripheral portion or refractive zone can be sharp anddiscontinuous. The height of the lens face sharply transitions fromsloping steadily downwards (e.g. across optical zones 930) to steppingvertically upwards (e.g. at transition zone 931), and the transitionsabruptly back to sloping steadily downward or substantially horizontalat outer refractive zone. In doing so, echelette 930 also has acharacteristic step height 932 defined by the distance between thelowest point and highest point of the echelette. Hence, the slope (orfirst derivative) and/or the curvature (second derivative) of thediffractive surface are discontinuous adjacent the transition. The firstderivative can be indicated by the direction of the lines, and thesecond derivative can be indicated by the curve of the line.

According to some embodiments, light comes from below, in the directionindicated by arrow A, and only hits the echelettes 930 of the profile.According to some embodiments, in theoretical terms light does not hitthe vertical connection of the optical zones, and hence the profile canbe said to have no transition zone. According to some embodiments, inpractice when one attempts to produce such a profile, for instance bylathe cutting, it may be difficult to reproduce the sharp corner (e.g.at where the optical zone connects with the adjacent optical zone) andhence the corner may be rounded to some extent due to the finite chiselradius. Such rounding may have a negligible effect on the opticalperformance. According to related embodiments, transition zone 931,which can be referred to as the transition from the echelette to theadjacent zone or zones, can be shaped in a specific way, so as tooptimize the optical performance, for example to minimize scatter from asharp transition.

Profile Parameters

The profile design can be characterized in terms of a set of parameters.For example, the limited echelette profile can be described as having acentral echelette with a diameter and surface area, an adjacentechelette(s) with the same surface area, and an associated step heightat each transition resulting in a phase delay. The central echelette mayhave a diameter within a range from about 1 mm to about 5 mm. Forexample, the central echelette may have a diameter of about 1.5 mm.Central echelette may have a surface area that is between 1 and 7 mm².For example, the central echelette may have a surface area that is 2.3mm². The peripheral echelette(s) may have a surface area equal to thecentral echelette. In particular, Table 1 discloses the dimensions ofthe radius and diameter of the central echelette, along with the surfacearea of the central and peripheral echelettes.

R (mm) De (mm) Area (mm²) 1.48 3 6.9 1.05 2.1 3.5 0.86 1.7 2.3 0.74 1.51.7 0.66 1.3 1.4 0.61 1.2 1.2

The step height or profile height can determine the phase delay or phaseshifting profile. A greater step height can correspond to a greaterphase shift. According to some embodiments, a lens can include atransition characterized by a step height producing a phase shiftbetween about 0.25 and about 1 times the design wavelength. In somecases, a diffractive profile can be characterized by a designwavelength, and the lens can include a transition characterized by astep height producing a phase shift between about 0.15 and about 2 timesthe design wavelength. According to some embodiments the lens mayinclude a transition characterized by a step height producing a phaseshift of about 0.5. In other embodiments, the lens may include atransition characterized by a step height of about 0.4.

Table 2 provides dimensions of various samples disclosing therelationship between phase delay (in wavelengths) and step height (inμm), as valid for an example IOL material.

TABLE 2 Phase Delay Step height 0.896 3.68 0.700 2.87 0.590 2.42 0.5092.09 0.500 2.05 0.423 1.74 0.366 1.50 0.350 1.44 0.250 1.03 0.150 0.62

FIG. 4B provides a graphical representation of a portion of a lensdiffractive profile with a central echelette and two peripheralechelettes according to embodiments of the present invention. The heightof the surface relief profile (from a plane perpendicular to the lightrays) of each point on the echelettes surface is plotted against thedistance from the optical axis of the lens. According to someembodiments, a lens with a central and peripheral adjacent echelette, asdisclosed in FIG. 4A may also be comprised of an additional peripheralechelette with a refractive region between the outermost echelette andthe interior echelettes.

FIG. 4C also details a portion of a lens diffractive profile with acentral echelette and two peripheral echelettes. In this embodiment,however, the refractive zone is immediately adjacent to the centralechelette and separates the central echelette from three peripheral andadjacent echelettes.

Although the above preferred embodiments disclose lenses with echelettesthat have equal step heights, preferred embodiments herein also includelenses with echelettes with varying step heights as detailed in, forexample, FIG. 4D. FIG. 4D. discloses a four echelette embodiment whereina refractive region separates the central and adjacent echelette fromthree peripheral adjacent echelettes. As seen in FIG. 4D, the stepheight (defined by the distance between the lowest point and highestpoint of the echelette) of the three outer echelettes is less than thestep height of the inner echelettes. Of course, in addition to coveringembodiments where the step height of the outer echelette(s) is less thanthe inner echelette(s), the step height of the inner echelette(s) may beless than the outer echelette(s). In addition, for embodiments withmultiple central rings, the central rings may have gradually changingstep heights. It is further envisioned that the rings in the peripherymay also have gradually changing step heights. It is also foreseeablethat the step heights may increase, decrease, or alternate.

FIG. 4E provides a graphical representation of a portion of a lensdiffractive profile with a central echelette and a peripheral echelettewhich is not adjacent to the central echelette. The central echelettemay have a shape or downward slope that is parabolic. A refractiveregion may then separate the central echelette from the peripheralechelette. The peripheral echelette may then be characterized by a sharpand discontinuous step height followed by a downward slope. As in theembodiments above, a peripheral refractive region may surround theoutermost echelette. Additionally, other exemplary embodiments includenon-adjacent echelette variations analogous to FIG. 4A-4D. By way ofnon-limiting example, two echelettes that are not separated by arefractive region may also be non-adjacent.

Pupil Dependence

The size of the human pupil varies with illumination. In bright lightthe pupil is small, and in dim or low light conditions the pupil islarge. In addition, the size of the human pupil varies withaccommodative effort. Without accommodative effort, the pupil is largerthan with accommodative effort. Hence, for a smaller pupil, it may bedesirable to provide a design that places a relative emphasis onintermediate or near vision. For a larger pupil, it may be desirable toprovide a design that places a relative emphasis on far vision.

In typical reading or near vision conditions where the light is bright,the size of the pupil is small, e.g. between about 1 mm and 2 mm indiameter, and the eye has a large depth of focus (for example from apinhole effect), almost irrespective of the optics of the IOL. When thesize of the pupil is large, e.g. larger than about 4-5 mm in diameter,the situation generally applies to low light conditions, and is oftenassociated with distance vision for which the power of the IOL istypically established. Therefore, many patients would benefit most froman IOL that enhances the depth of focus in order to view at intermediatedistances. An IOL having a central echelette with limited adjacentechelettes may effectively increase the depth of focus for intermediatepupil sizes, while maintaining the general increased depth of focus ofsmall pupil sizes, and also maintaining an emphasis on far vision forlarge pupil sizes.

At the same time, since the limited echelettes and the remaining surfacearea of the optic or remaining lens portion (“non-echelette”) haveunequal surface areas for almost all pupil sizes, there is an incompletesplit between the foci. The condition of dysphotopsia (e.g. halos) thatis present for multifocal lenses is observed to be dominated byseparation of two foci and pupil size effects. Accordingly, pursuant toexemplary embodiments of the present invention, the lens may includeonly a limited number of echelettes, so that light separation betweendistinct foci is not complete, as compared to standard diffractivemultifocal IOLs. Since the split of light is incomplete, the separationof foci is incomplete. The incomplete separation of foci contributes tothe extended depth of focus and the attenuation of dysphotopsia (e.g.halos).

In an exemplary embodiment, the limited echelette design has an opticalperformance that depends on the pupil size. For very small pupils, wherethe pupil is smaller than the size of the central and adjacentechelette(s), the echelette will act as a refractive lens, having a verylarge depth of focus due to the pinhole effect. For medium and higherpupil sizes, where the pupil covers the central echelette and theadjacent echelette, the lens will act as a diffractive/refractive lens,directing the light to several foci. For higher pupil sizes, more lightis being directed to the lower order foci. The size of the central andadjacent echelette(s) influences the pupil dependence of the lens. Assuch, the size of the central and adjacent echelette(s) can be chosen,depending on the pupil sizes of a specific patient. For example, thepupil sizes of a patient may be measured in bright light, in dim light,during far vision and during near vision, and in the differentcombinations of light level and accommodative effort. These differentpupil sizes, which may be defined as pupil dynamics, can be used asinput parameters for an optimal design of the limited echelette design.

For example, if a patient has a pupil diameter during near vision (e.g.viewing target at close distance, with high accommodative effort)smaller than 2 mm, having this pupil dimension with both bright and dimlight, then the size of the central and adjacent echelette(s) may beselected to be smaller than 2 mm (e.g. outer diameter of the adjacentechelette of FIG. 4A), as to provide adequate near and intermediatevision. Relatedly, if a patient has a pupil diameter during near visionlarger than 2 mm, having this pupil dimension with both bright and dimlight, then the size of the central and adjacent echelette(s) may be 2mm or larger, as to provide adequate near and intermediate vision. Ingeneral, the diameter of the central and adjacent echelette(s) can besmaller than the smallest pupil size the patient has under any condition(e.g. bright/dim light; near/far vision). For any type of pupildynamics, the size, the profile, and the offsets may be chosen tomaximize the lens performance for that specific patient, or group ofpatients. Generally, this is a trade off between the different visioncircumstances (combinations of light level and accommodative effort) atwhich the pupil of the patient is measured. Accordingly, exemplaryembodiments include a method of designing an ophthalmic lens comprisedof utilizing pupil size measurements and based on the measurementsdetermining the size of an isolated echelette to impose on the surfaceof a lens. The pupil size measurements may be based on a group ofpatients.

Evaluation of Variations of a Specific Example

FIGS. 5 and 6 show calculated defocus curves in the ACE eye model of anembodiment with a central ring diameter of 1.48 mm, an echelette surfacearea of 1.7 mm², and a phase delay of 0.4 wavelength. The horizontalaxis denotes the defocus value in the image plane, in millimeters.Negative defocus values represent the myopic eye, and therefore,simulate vision at intermediate and near distances. The vertical axisdenotes the modulus (MTF) at 50 cycles per millimeter. Data for 5 mmpupil diameters is included. FIG. 5 shows the defocus curve for anembodiment having only a single central echelette. FIG. 6 shows anexemplary embodiment as disclosed in section 4E, having, in addition tothe central echelette, a peripheral echelette. The peripheral echeletteand has a surface area of 3.5 mm², and a phase delay of 0.82 wavelength.The MTF at intermediate vision distances, with defocus values of about−0.2 mm to −0.3 mm, as shown in FIG. 6 is higher than the MTF atcorresponding defocus values in FIG. 5. As illustrated in the figures, acentral plus peripheral echelette increases the depth of focus ascompared to a central echelette only.

Embodiments of the present invention may be combined with a multifocallens design, and with that extend the depth of focus of each focus ofthe multifocal lens. Similarly, embodiments of the present invention maybe combined with an accommodating lens design, by which the range ofaccommodation of the accommodating lens can be extended. In addition,embodiments of the present invention may be combined with lensescorrecting ocular aberrations, like toric lenses, aspherical lenses,lenses correcting chromatic aberrations, and the like.

Embodiments of the present invention may be combined with a lens designcorrecting chromatic aberrations. In one embodiment, the phase delay ofthe echelettes in the preceding examples is increased by a discretemultiple of wavelengths, in order to correct for chromatic aberration.For example, if a phase delay of 0.5 was used, corresponding to a stepheight of 2.05 μm, an alternative embodiment would have a phase delay of1.5, corresponding to a step height of 6.15 μm. This embodiment directsthe first order diffraction to the far focus, and the second orderdiffraction establishes the depth of focus at the intermediate and nearrange.

Further Aspects of Multi-Ring Lenses for Extended Depth of Focus

Embodiments of the present invention encompass ophthalmic lenses havingan aspheric anterior surface and a diffractive posterior surface, whichprovide extended depth of focus and compensate for natural chromatic andspherical aberration produced by the eye. Although many of the examplesprovided herein describe a diffractive profile disposed at the posteriorof an ophthalmic lens, it is understood that a diffractive profile canalso be disposed at the anterior lens surface, or in some cases at bothanterior and posterior surfaces, with similar results. Similarly,although many of the examples provided herein describe an asphericalanterior surface, it is understood that an aspherical profile can alsobe disposed at the posterior lens surface, or in some cases at bothanterior and posterior surface, with similar results. Exemplaryophthalmic lenses include contact lenses, phakic lenses, pseudophakiclenses, corneal inlays, and the like.

FIG. 7 depicts an exemplary ophthalmic lens 700 having an anteriorsurface 710 and a posterior surface 720. Each of the anterior andposterior surfaces are disposed about an optical axis 715. The anteriorsurface can incorporate an aspheric shape, and the posterior surface canincorporate a diffractive shape. In some instances, lens 700 may have abi-convex configuration (e.g. FIG. 7-1), where each of the anterior andposterior surfaces presents a generally convex shape or profile. Theanterior surface 710 can include an aspheric shape that extends acrossthe entire front of the lens. Hence, an aspheric anterior surface 710may include a full anterior surface that is refractive. Similarly, theposterior surface 720 can include a diffractive profile that extendsacross the entire back of the lens. Hence, the posterior optical surface720 may include a diffractive profile that extends across the entireposterior surface. The anterior surface 710 operates to refractivelydirect light toward the far field focus 730. In this way, the far focus730 may correspond to a refractive aspect of the lens 700. The posteriorsurface operates to diffractively direct light toward the far fieldfocus 730 and the intermediate focus 740. In this way, each of the farfocus 730 and the intermediate focus 740 may correspond to a diffractiveaspect of the lens. An aspheric shape can provide a means for fully orat least partially compensating for or treating natural sphericalaberration which may be produced by the eye (e.g. ocular sphericalaberration or corneal spherical aberration). The diffractive profile canprovide a means for fully or at least partially compensating for ortreating natural chromatic aberration which may be produced by the eye(e.g. ocular chromatic aberration). In some instances, the means forcompensating for ocular chromatic aberration and the means forcompensating for ocular spherical aberration, when combined, provide afar focus corresponding to a base power and an intermediate focuscorresponding to an add power. The difference between the base power andthe add power can define an extended depth of focus for the lens.

The far field focus 730 may correspond to a base power of the lens, andthe intermediate focus 740 may correspond to an add power of the lens.In some cases, the far focus 730 corresponds to a first diffractiveorder of the diffractive profile. Optionally, the far focus 730 maycorrespond to a second diffractive order of the diffractive profile.Similarly, the far focus may correspond to a third diffractive order ofthe diffractive profile. Often, the intermediate focus 740 correspondsto a diffractive order (e.g. 2^(nd)) of the diffractive profile that ishigher than the diffractive order (e.g. 1^(st)) corresponding to the farfocus 730. The base power value for the lens may vary depending on thetype of lens. Similarly, the add power for the lens may vary dependingon the type of lens. For an intraocular lens, the base power value maybe within a range between 5 to 34 Diopters, or even wider. For a contactlens, the base power value may be within a range between −10 to +5Diopters or even wider. For an exemplary intraocular lens, the basepower can be 20 Diopters, and the add power can be 1.75 Diopters. It isunderstood that other similar add powers corresponding to theintermediate focus can be used. Such an add power is substantially lowerthan many current multifocal intraocular lenses, which often provide anadd power in the range from 3.0 to 4.0 Diopters. For an exemplarycontact lens, the add power may be about 1.3 Diopters.

As shown here, the diffractive profile includes a central diffractivezone 750 and an outer or peripheral diffractive zone 760. The centralzone 750 encompasses two inner echelettes, or rings, having diameters of1.6 mm and 2.2 respectively. The central zone 750 operates to direct 41%of incident or incoming light to far field focus 730, and 41% ofincident or incoming light to intermediate focus 740. In this sense, thecentral zone 750 can be said to provide a light distribution between farand intermediate of 50:50%. That is, the percentage of light directed toeach of the far and intermediate focus points is 50% of the sum of thelight distributed between the far focus and intermediate focus (i.e.41/(41+41)=50%). It is understood that other diffractive profile centralzones providing different light distributions may be used.

The peripheral zone 760 operates to direct 63% of incident or incominglight to far field focus 730, and 21% of incident or incoming light tointermediate focus 740. In this sense, the peripheral zone 760 can besaid to provide a light distribution between far and intermediate of75:25%. That is, the percentage of light directed to the far focus is75% of the sum of the light distributed to the far focus andintermediate focus (i.e. 63/(63+21)=75%), and the percentage of lightdirected to the intermediate focus is 25% of the sum of the lightdistributed between the far focus and intermediate focus (i.e.21/(63+21)=25%). It is understood that other diffractive profileperipheral zones providing different light distributions may be used.

In this way, the diffractive optical element includes multiple zones,where each zone acts to concentrate or direct incident light in specificdirections according to specific diffractive orders. In some instances,about 16% to 18% of the light is lost to spurious diffractive orders.According to some embodiments, the zeroth order is not used for visiontreatment purposes.

The lens 700 provides an extended depth of focus to an eye of a patient.For example, the lens can bring faraway objects and objects atintermediate distances into focus for the patient simultaneously. Whenthe lens is administered to the patient, the patient will not perceivetwo distinct focal images (e.g. two images corresponding to far andintermediate focus, respectively), but rather will experience a trueextended depth of focus, with a constant or gradual decrease in visualquality when objects become closer to the eye. FIGS. 12A, 12B, and 13,discussed elsewhere herein, demonstrate how exemplary lens designs canimprove optical quality across an extended depth of focus.

By combining an aspheric anterior surface that corrects for sphericalaberration, and posterior diffractive surface that corrects forchromatic aberration, lenses as disclosed herein provide excellentcontrast properties in addition to an extended depth of focus. Forexample, the diffractive surface combined with the aspheric surface cancorrect or reduce chromatic aberration produced by the eye at variousfoci.

It is understood that in some embodiments, correction or treatment ofchromatic aberration can also be achieved by providing a lens containinga combination of two materials having different dispersioncharacteristics, for example as described by Bradley et al.“Achromatizing the human eye” Optom. Vis. Sci. 68, 608-16 (1991), thecontent of which is incorporated herein by reference. For example, lensdesign can use pairings of materials that have the same refractive indexat some intermediate wavelength, e.g., 588 nm, but different amounts ofchromatic dispersion to create lenses with zero power at 588 nm but withopposite power at wavelengths above and below 588 nm. An alternativeembodiment of the present invention involves the correction of chromaticaberration using two materials having different dispersioncharacteristics, in combination with an aspherical refractive surfaceand diffractive rings to extend the depth of focus.

Embodiments of the present invention encompass ophthalmic lenses andlens prescriptions, as well as systems and methods for producing suchlenses and prescriptions. Exemplary lenses include lens surfaces,disposed about an optical axis, which provide aspheric and diffractiveprofiles. The aspheric profile can direct light toward a far focus, andthe diffractive profile includes (i) a central zone that distributes afirst percentage of light toward a diffractive order at the far focusand a second percentage of light toward another diffractive order at anintermediate focus disposed anterior to the far focus, and (ii) aperipheral zone, surrounding the central zone, that distributes a firstpercentage of light toward the diffractive order at the far focus and asecond percentage of light toward the other diffractive order at theintermediate focus. In some instances, the aspheric profile is providedby an anterior face of the lens. In some cases, the diffractive profileis provided by the posterior face of the lens.

As noted elsewhere herein, different diffractive zones can providedifferent light distributions to different focus points (e.g. betweenfar and intermediate). Table 3 provides an illustrative example.

TABLE 3 Far Intermediate (1^(st) diffractive (2^(nd) diffractiveDistribution Zone order) order) (Far:Intermediate) Central 41% 41% 50:50Peripheral 63% 21% 75:25

As noted elsewhere herein, the intermediate focus corresponds to the addpower. Hence, lens designs such as those represented by Table 3 aredifferent than currently known lens designs which the entirety of thelens directs 50% of the light toward the add power. Such known lensdesigns may not sufficiently correct or treat chromatic aberration inthe far focus. Further, such known lens designs have an add power thatis substantially larger than that provided by embodiments of the presentinvention. In some instances of the present invention, exemplary lensdesigns include a peripheral zone which directs 25% of the distributedlight toward the add power. What is more, because lens designs accordingto embodiments of the present invention may provide a diffractiveprofile across the entire lens or a substantial portion thereof, suchlenses are different than currently known lens designs which do notprovide a diffractive profile or diffractive effect at large pupilsizes.

FIG. 8 illustrates aspects of a diffractive profile 800 of an ophthalmiclens according to embodiments of the present invention. As shown here, acenter portion or (first) echelette 802 of the diffractive profile has aheight (h₁) relative to a base shape or curvature 804 of the profile. Asecond echelette 810 is disposed peripherally adjacent to the firstechelette 802, with a first transition zone 811 disposed therebetween.The transition zone 811 can be characterized by a step height (h₂).Hence, each echelette can have a characteristic height or step height,for example as defined by the distance between the inner (or central),highest point of the echelette (e.g. as measured relative to the baseshape), and the outer (or peripheral), lowest point of the echelette(e.g. as measured relative to the base shape). As shown here, the lowerpoint of the echelette can correspond to the location of the base shape.In this example, the step height of the center or first echelette 802 is(h₁), the step height of the second peripheral echelette 810 is (h₂),the step height of the third peripheral echelette 820 is (h₃), the stepheight of the fourth peripheral echelette 830 is (h₄), and the stepheight of the fifth peripheral echelette 840 is (h₅). FIG. 8-1 shows arelated diffractive profile embodiment, here depicted relative to aconvex posterior base.

In some instances, a diffractive profile includes 9 rings on a 5 mmdiameter optic surface. The diffractive profile can include two centralrings each having a step height that is larger than the step heights ofthe other seven peripheral rings. The diffractive profile can provide amonofocal diffractive surface that at least partially corrects orcompensates for natural chromatic aberration produced by the patient'seye. The aspheric anterior surface of the ophthalmic lens can operate tocorrect or treat spherical aberration of the eye. In some instances,lens system and methods embodiments of the present invention mayincorporate features of lenses and treatments disclosed in U.S. Pat. No.6,830,332, which discusses lenses having both aspheric anterior surfacesand diffractive posterior surfaces. In some cases, lens designs may alsoincorporate diffractive surfaces, for example which direct 63% of thetotal light to the far focus and 21% to a near or intermediate focus. Insome instances, a diffractive surface can provide an add power of 1.75D, with a central 2.2 mm diameter zone that directs 41% of the totallight to far focus and 41% to intermediate focus, surrounded by an outerzone which directs 63% of the total light to the far focus and 21% tothe intermediate focus. Exemplary diffractive surfaces can be pupilindependent, have an add power of 1.75 Diopters, and provide a centralzone light distribution between the far focus and the intermediate focusof 50%:50% and a peripheral zone light distribution between the farfocus and the intermediate focus of 75%:25%. In optical terms, thediffractive profile provides a plurality of foci.

In some embodiments, the diffractive profile 800 can be represented asthe incorporation of two diffractive echelettes 802 and 810 on top of abase ophthalmic lens configuration. FIG. 8A provides a schematicillustration of such a construction. Here, the upper graph 810 acorresponds to a first or base diffractive profile having an equal stepheight across the entire optical surface, and the middle graph 820 acorresponds to a second diffractive profile having two centralechelettes or rings (which may also have equal step heights). A similarsecond diffractive profile is depicted in FIG. 8B (the base is shownhaving a convex shape, and the central echelettes are below the baseradius). The lower graph 830 a corresponds to a third diffractiveprofile based on the combination of the first and second diffractiveprofiles. Relatedly, FIG. 8C provides a schematic illustration of afinal diffractive profile that combines two diffractive profiles. FIGS.8D and 8E also show aspects of exemplary diffractive profiles, accordingto embodiments of the present invention. In FIG. 8D, the echelettes ofthe central zone may extend into or anterior to the convex base. Thefirst (center) echelette and the second echelette can both extendsimilar or equal distances from the posterior base. Or, the firstechelette can extend posterior to the second echelette. Or, the secondechelette can extend posterior to the first echelette. As seen in FIG.8E, the first echelette may extend posterior to the posterior base atvarious distances relative to the second or other peripheral echelettes.It is also envisioned that some or all of the echelettes will extendinto (or anterior to) the convex base.

A base ophthalmic lens configuration may include a diffractive surfaceprofile such as that described in U.S. Pat. No. 6,830,332, incorporatedherein by reference. For example, the base lens configuration mayinclude an achromatic design having a profile height that is equal toone wavelength, as discussed at column 4, lines 42-43 of the '332patent. Embodiments of the present invention encompass designs thatinclude extended depth of focus (EDOF) step heights that are placed ontop of such an achromatic design.

In some instances, a base ophthalmic lens configuration may incorporatea pupil independent diffractive profile over the entire optic. Hence,the lens can continue to provide excellent intermediate visionproperties as the pupil widens in low light conditions. This pupilindependent diffractive profile may have the same ring structure (addpower) as the two echelettes. As a result, the two echelettes show up astwo central echelettes having higher profile height (step height) on anotherwise constant-height diffractive profile.

In some instances, each echelette or ring has a step height or profileheight that is larger than one wavelength. For example, a wavelength canbe 550 nm, as that described in U.S. Pat. No. 6,830,332, incorporatedherein by reference. Accordingly, the diffractive profile can operate todistribute incident or incoming light substantially or predominately tothe first and second diffractive orders, for example to far focus 730and intermediate focus 740 of FIG. 7, respectively.

In some instances, a diffractive profile of an ophthalmic lens produceschromatic aberration in light directed to the first and seconddiffractive orders that is opposite in sign to the chromatic aberrationproduced by the natural eye (e.g. a natural phakic or aphakic eye intowhich an intra-ocular lens is eventually placed). Hence, the diffractiveprofile can operate to at least partially correct, offset, or otherwisetreat the eye's natural chromatic aberration. For example, optical partsof a patient's aphakic eye 900 may introduce chromatic aberration asdepicted in FIG. 9A by focusing different wavelengths of light (e.g.blue light 902, green light 904, and red light 906) to different focalpositions, respectively. Hence, it can be seen that the patient's owneye can produce chromatic aberration, where the chromatic aberrationproduced by the eye causes different wavelengths of light to havediffering focal lengths.

As depicted here, FIGS. 9A and 9B are schematic drawings, and the focalpoints or regions (e.g. 920 a, 920 b respectively) are shown at thecenter of the eye for purposes of clarity. Normally, the focal point orarea is at, or close to, the retina at the posterior of the eye.

By introducing an ophthalmic lens 910 as depicted in FIG. 9B, it ispossible to counteract the natural chromatic aberration of the eye, andas a result bring multiple wavelengths of the visible spectrum toward asingle focal point (e.g. 920 b). Hence, the pseudophakic eye of FIG. 9Bprovides an improvement in the quality of images seen by the patient.The light at different wavelengths is now aligned, or more aligned, ascompared with FIG. 9A. In this way, the ophthalmic lens 910 operates tocompensate for chromatic aberration produced by the eye (e.g. ocularchromatic aberration). It is understood that ophthalmic lenses asdisclosed herein can correct or treat chromatic aberration at one ormore diffractive orders or foci.

In some instances, light rays at the periphery of the patient eye (e.g.cornea) may be over-refracted, thus producing a region of defocusedlight that decreases image quality, for example due to sphericalaberration. In some cases, the cornea, optionally in combination withother optical parts of the eye, can produce spherical aberration. Hence,spherical aberration may in various instances be referred to as cornealspherical aberration or ocular spherical aberration. An aspheric surfaceof the ophthalmic lens can compensate for such spherical aberration, byreducing the amount by which the peripheral light rays are refracted.For example, as shown in FIG. 9B, an aspheric optical surface of thelens 910 can compensate for a region of defocused light and therebycreate a properly or improved focused point of light toward the retinaor posterior of the eye, as indicated by arrow A. As shown here, inaddition to compensating for ocular chromatic aberration, the ophthalmiclens also operates to compensate for ocular spherical aberration, anddelivers more accurately focused light toward the posterior of the eye.

According to some embodiments, an ophthalmic lens 900 can operate totreat or correct chromatic aberration over a range of foci, or over anextended depth of focus. For example, an ophthalmic lens can provide apartial correction or treatment of chromatic aberration in the far focus(e.g. focus 730 of FIG. 7), and a substantially larger or fullcorrection or treatment of chromatic aberration in the intermediatefocus (e.g. focus 740 of FIG. 7). Such treatment of chromatic aberrationcan be achieved by using a specific diffractive power.

For example, let the n^(th) diffractive order be associated with the farfocus of the ophthalmic lens, and the j^(th) diffractive order beassociated with the intermediate focus (focus range) of the ophthalmiclens. The difference between the orders is j-n. For an extended depth offocus lens, the difference in lens power (e.g. in unit of Diopters)between the intermediate and the far vision denotes the range ofextended depth of focus.

Relatedly, let the chromatic aberration of the ophthalmic lens in then^(th) diffractive order, or far focus, be characterized as LCA_(f) withthe following equation:LCA_(f)=LCA_(r) +n*LCA_(d)

Here, LCA_(r) refers to the longitudinal chromatic aberration of therefractive base lens and LCA_(d) refers to the longitudinal chromaticaberration of the diffractive profile. It is noted that the aboveequation includes a “+” sign, however the value of LCA_(d) in theequation is negative.

Similarly, the chromatic aberration of the diffractive focus for thej^(th) diffractive order, or intermediate vision, can be characterizedas LCA_(i) with the following equation:LCA_(i)=LCA_(r) +j*LCA_(d).

For designs having correction of ocular chromatic aberration, LCA_(f)and LCA_(i) should have negative values.

Let the chromatic aberration of the aphakic eye be LCA_(ae). Correctionof the ocular chromatic aberration, without over-correction is obtainedif:−LCA_(f)≦LCA_(ae)and−LCA_(i)≦LCA_(ae)Or:n≦(LCA_(ae)+LCA_(r))/(−LCA_(d))j≦(LCA_(ae)+LCA_(r))/(−LCA_(d))

For example, with a diffractive profile having positive diffractiveorders, LCA_(ae)=2 D, LCA_(r)=1.5 D and LCA_(d)=−1.75 D. Full chromaticaberration is obtained in the intermediate vision for the diffractionorder of j=(2+1.5)/1.75=2. In such a case, the first diffractive orderleaves the eye with a LCA of (2+1.5−1*1.75)=1.75 D, and giving areduction of LCA by 1.75 D of the pseudophakic eye (e.g. artificial lensimplanted), and 0.25 D reduction of the aphakic eye (e.g. natural lensremoved).

Table 4 provides step height, diameter, optical path difference (OPD inwavelength λ) and light distribution values for an exemplary diffractiveprofile, according to embodiments of the present invention.

TABLE 4 Outer Light Distribution Echelette Step Height Diameter OPD(1^(ST):2^(ND)) 1st/Center h₁ = 0.0062 mm 1.60 mm  1.5 λ two combined2nd h₂ = 0.0062 mm 2.20 mm  1.5 λ echelettes provide 41% to 1^(st) orderand 41% to 2^(nd) order (for a distribution between 1^(st) and 2^(nd) of50:50) 3rd h₃ = 0.0062 mm 2.75 mm  1.5 λ seven combined 4th h₄ = 0.0056mm 3.17 mm 1.366 λ echelettes provide 5th h₅ = 0.0056 mm 3.55 mm 1.366 λ63% to first order 6th h₆ = 0.0056 mm 3.88 mm 1.366 λ and 21% to 2^(nd)7th h₇ = 0.0056 mm 4.20 mm 1.366 λ order (for a 8th h₈ = 0.0056 mm 4.48mm 1.366 λ distribution between 9th h₉ = 0.0056 mm 4.76 mm 1.366 λ1^(st) and 2^(nd) of 75:25)

According to some embodiments, the step heights are configured so thatthe lens generally functions using the 1^(st) and 2^(nd) diffractiveorders. The specific step heights used may depend on the refractiveindex of the material present in the lens, and/or the wavelengthconsidered. Typically, each step height creates a difference in opticalpath length. Hence, assuming that the refractive index of the aqueous ofthe eye is 1.336, and considering an ophthalmic lens material having arefractive index 1.47, an approximately four micron step heightintroduces an optical path difference of one wavelength. In someinstances, embodiments of the present invention encompass lens designshaving step height values greater than four microns. In some instances,embodiments of the present invention encompass lens designs having stepheight values within a range between four and 8 microns. In someinstances, embodiments of the present invention encompass lens designshaving echelette step heights that introduce optical path differencevalues that are greater than one.

As indicated in Table 4, an exemplary ophthalmic lens can include acentral zone having two echelettes that operate to direct light betweenfar and intermediate foci at a 50:50 relative ratio for an EDOF effectat small and medium pupil sizes. The further peripheral echelettesoperate in combination to direct light between far and intermediate fociat a 75:25 relative ratio, which can maintain an EDOF effect for largerpupil sizes.

FIGS. 10A and 10B show modulation transfer function (MTF) curves forophthalmic lens configurations according to embodiments of the presentinvention (i.e. Xring 313, Xring 329, and Xring 305), as compared withother single ring intraocular lens designs (i.e. 1R001 and 1R002) andstandard multifocal intraocular lens designs. Exemplary single ringdesigns are described in previously incorporated U.S. Patent ApplicationNo. 61/288,255 filed Dec. 18, 2009. Hence, the through focusperformance, in white light, of the various designs can be compared.These graphs are based on measurements of prototype lenses, placed in aneye model that is similar to a modified ISO model, as described inNorrby et al., “Model eyes for evaluation of intraocular lenses” Appl.Opt. 46(26): 6595-605 (2007), the content of which is incorporatedherein by reference. FIG. 10A illustrates the through focus performanceof the lenses at a pupil diameter of 3 mm (e.g. medium pupil size), andFIG. 10B illustrates the through focus performance of the lenses at apupil diameter of 5 mm (e.g. large pupil size). The large pupil sizerepresents a pupil size under low light conditions. The vertical axisdenotes the modulation (MTF) at 50 cycles per millimeter. The horizontalaxis denotes the defocus in the spectacle plane. Defocus in thespectacle plane can be translated into viewing distance, roughly by theequation (viewing distance in centimeters)=100/(defocus in the spectacleplane). For instance, a defocus of 1.33 Diopters in the spectacle planecorresponds with 100/1.33=75 centimeters viewing distance.

As shown here, the peak 1010 at intermediate focus (about 1.3 Dioptersin the spectacle plane) can change in the horizontal position, bychanging the diffractive add power of the ophthalmic lens. For example,adjusting the echelette diameters of the central and outer diffractivezones (e.g. as shown in FIG. 7) can operate to change the diffractiveadd power. The peak 1010 at the intermediate focus can also change inthe vertical position, by changing the light distribution of theophthalmic lens. For example, adjusting the step heights of the centraland outer diffractive zones (e.g. as shown in FIG. 7) can operate tochange the light distribution percentage at the intermediate focus.

Relatedly, the peak 1020 at far focus (0 Diopters) can change in thevertical position, by changing the light distribution of the ophthalmiclens. For example, adjusting the step heights of the central and outerdiffractive zones (e.g. as shown in FIG. 7) can operate to change thelight distribution percentage at the far focus. That is, directing ahigher percentage of light to the far focus will increase the height ofpeak 1020 upward, and directing a lower percentage of light to the farfocus will decrease the height of peak 1020.

Hence, according to some embodiments, variations in lens step heightscan operate to change light distribution properties of the lens, andwith that, the vertical positions of 1010 and 1020. Further, variationsin ring diameters can operate to change the add power properties of thelens, and with that, the horizontal positions of 1010.

The result of these variations are shown in FIGS. 10A and 10B, in whichthree lens design embodiments according to the present invention(annotated as “Xring”) having different add powers and lightdistributions are shown. The lens corresponding to the line labeled with“Xring 313” has 2.5 Diopter add power, the lens corresponding to theline labeled with “Xring 329” has 1.75 Diopter add power, and the lenscorresponding to the line labeled with “Xring 305” has 1.5 Diopter addpower. As depicted here, the 1.75 Diopter design of the Xring 329 lenshas an intermediate peak at about 1.3 Diopters, as the horizontal axisdenotes defocus in the spectacle plane. As a general rule, defocus inthe spectacle plane is about ¾ of defocus in the intraocular lens plane(e.g. ¾*1.75≈1.3). In this sense, the intraocular lens add power of 1.75Diopters can be distinguished from the spectacle plane defocus of 1.3 D.

Additional details regarding the use of modulation transfer function(MTF) to evaluate the performance of a visual system (e.g. ophthalmiclens and/or other optical parts of the eye) are described in U.S. PatentPublication No. 2009/0210054, which is incorporated herein by reference.

FIGS. 11A and 11B show modulation transfer function (MTF) data forvarious ophthalmic lens configurations according to embodiments of thepresent invention (e.g. Xring designs 302 to 311, 314, and 329), ascompared with two regular multifocal intraocular lens designs. As shownhere, the MTF values at far focus for the ophthalmic lenses according toembodiments of the present invention (e.g. Xring designs) are betterthan the MTF values at far focus for these multifocal intraocular lensdesigns. For a 3 mm pupil, the MTF of embodiments of the presentinvention is 18% to 83% higher than that of current regular multifocallenses. For a 5 mm pupil, the MTF of embodiments of the presentinvention is 39% to 173% higher than that of current regular multifocallenses.

FIG. 12A provides an illustration of US Air Force images by defocus fora 3-mm pupil diameter, for various lens design configurations. Defocusvalues are provided in Diopters, in the spectacle plane. As shown here,the Xring designs (307, 311, 314, and 329) provide better results than amultifocal intraocular lens design, a monofocal lens design, and twosingle ring designs (1R001 and 1R002). The four different Xring designsdepicted here each have different add power and light distributions.Xring 307 has an add power of 1.5 Diopters, Xring 311 has an add powerof 2.0 Diopters, Xring 314 has an add power of 2.5 Diopters, and Xring329 has an add power of 1.75 Diopters.

Model eye data demonstrating that a single ring ophthalmic lens designcan provide an extended depth of field effect is provide in previouslyincorporated U.S. Patent Application No. 61/288,255 filed Dec. 18, 2009.FIG. 12A provides defocus images of the US Air Force target,corresponding to two intraocular lens designs according U.S. 61/288,255(e.g. 1R001 AND 1R002) and a regular monofocal aspheric intraocular lensdesign (“Monofocal” in FIG. 12), in a modified ISO eye model asdescribed in the previously incorporated Norrby et al., “Model eyes forevaluation of intraocular lenses” Appl. Opt. 46(26): 6595-605 (2007). Asdepicted here, under defocus, the images corresponding to the 1R001 and1R002 IOL designs are less blurred when the eye is defocused, ascompared to those of the monofocal lens design. Up to at least −2.00Diopters of defocus, some of the horizontal and vertical bars can stillbe distinguished with the 1R001 and 1R002 designs. In contrast, for theregular monofocal IOL design, the horizontal and vertical bars can bedistinguished only up to less than −1.00 Diopters. These pictures weretaken with white light. It may be helpful to evaluate or refer toclinical results in terms of the size of the EDOF effect. The Xringdesigns are intended to provide an enhanced EDOF effect. FIG. 12B showthe area under the MTF curve, up to 25 c/mm, when an exemplary lens ofthe current invention is measured in this same modified ISO eye model.The exemplary lens in FIG. 12B has a base lens configuration with anachromatic design on the posterior side of the lens. The achromaticdesign has a profile height that is equal to one wavelength. The EDOFdesign is placed on top of the achromatic design. The EDOF design ofFIG. 12B is seen in Table 4. Finally, an aspheric shape on the anteriorside of the lens reduces spherical aberration. The combination resultsin the MTF curve seen in FIG. 12B. FIG. 12B also shows the measurementresults of a regular multifocal lens. The graph illustrates that, asopposed to a regular multifocal lens, which has two distinct peaks witha valley in between representing two distinct focal points, the currentdesign has one broad peak over an extended range of vision representinga gradual change of image quality over the extended range. Thisillustrates that IOLs according to the present invention behave in awell-defined different manner compared to regular multifocal lenses.

The images of FIG. 12 show only part of the range of the exemplary lensaccording to embodiments of the present invention. In some cases, amultifocal lens has a second sharp image at about −3 Diopters defocus.In between the best focus (0 Diopter) and the second focus at −3Diopters, the multifocal lens may show highly blurred images. However,it should be realized that for a multifocal lens, the visual function atintermediate distances is still at a functional level, with a visualacuity that is often better than 20/40. This observation can be held inmind when evaluating the images, as well as those representing designsaccording to embodiments of the present invention.

For example, with the Xring 311 design, the USAF image at −1.50 Diopterdefocus is sharper than the image at −1.0 Diopter defocus. The magnitudeof this feature is much smaller than what is observed for a multifocallens. That is, the sharpness difference between −1.50 Diopters and −1.00Diopter is smaller for the Xring design and larger for the multifocaldesign. Moreover, the overall sharpness throughout this range is higherfor the Xring design as compared to the multifocal design. Therefore, itcan be expected that in clinical terms, functional vision at the entireintermediate range is comparable to that at best focus, with a visualacuity of around 20/20. For example, for Xring 311, the intermediaterange is estimated to run from 0 to at least −1.75 Diopters.

Various techniques for evaluating the depth of focus in a visual system(e.g. ophthalmic lens and/or other optical parts of the eye) aredescribed in U.S. Patent Publication No. 2009/0210054, which isincorporated herein by reference.

Ophthalmic lens embodiments of the present invention can be configuredto compensate for various aberrations produced by a patient eye, such asspherical and chromatic aberration, which may derive from the corneaand/or other optical parts of the patient eye. Hence, methods ofdesigning and/or fabricating such lenses may involve obtaining or usingdata related to aberrations of the patient eye. Any of a variety ofaberrometers, including wavefront measurement systems, may be used toobtain such aberration data. The components of an exemplary wavefrontmeasurement system for measuring the eye and aberrations may compriseelements of a WaveScan® system, available from AMO MANUFACTURING USA,LLC, Milpitas, Calif. One embodiment includes a WaveScan system with adeformable mirror. An alternate embodiment of a wavefront measuringsystem is described in U.S. Pat. No. 6,271,915, the full disclosure ofwhich is incorporated herein by reference. It is appreciated that anywavefront aberrometer could be employed for use with embodiments of thepresent invention. Relatedly, embodiments of the present inventionencompass the implementation of any of a variety of optical instrumentsprovided by AMO WAVEFRONT SCIENCES, LLC, including the COAS wavefrontaberrometer, the ClearWave contact lens aberrometer, the CrystalWave IOLaberrometer, and the like.

In some cases, embodiments of the present invention encompass systems,kits, and computer program products for manufacturing or fabricatingophthalmic lenses as disclosed herein. Ophthalmic lenses can befabricated using laser ablation processes, and/or may incorporatestandard techniques for the manufacture of intraocular lenses, aspectsof which are described in U.S. Pat. Nos. 4,856,234, 5,322,649, and5,888,122, as well as U.S. Patent Publication No. 2002/0082690. Thecontent of each of these patent publications is incorporated herein byreference. Relatedly, in some instances manufacturing or fabricationprocesses may include aspects of molding, polishing, measuring of thepower, quality control, modeling, and the like.

FIG. 13 depicts aspects of an exemplary method 1300 for generating anophthalmic lens prescription according to embodiments of the presentinvention. In some cases, the method may include measuring sphericaland/or aberrations of a patient eye. As shown here, the method mayinclude inputting a patient parameter data profile as indicated by step1330. The data profile may include (a) a patient spherical aberrationparameter corresponding to a measured patient spherical aberration 1310and (b) a patient chromatic aberration parameter corresponding to ameasured patient chromatic aberration 1320. Further, the method mayinclude generating the ophthalmic lens prescription for the patient asindicated by step 1340. The ophthalmic lens prescription may beconfigured to compensate for the measured patient spherical andchromatic aberrations and to provide an extended depth of focus. In somecases, so as to provide the extended depth of focus, the prescriptionmay provide a far focus corresponding to a base power and anintermediate focus corresponding to an add power, where a differencebetween the base power and the add power defines an extended depth offocus for the ophthalmic lens prescription. In some cases, so as toprovide the extended depth of focus, the prescription may provide amodulation transfer function value at 50 cycles per millimeter of atleast 10, for an intermediate focus, at 3 mm and 5 mm pupil diameters.

FIG. 14 depicts aspects of an exemplary method 1400 for fabricating anophthalmic lens according to embodiments of the present invention. Asshown here, the method includes inputting an ophthalmic lensprescription for a patient as indicated by step 1410, and fabricatingthe ophthalmic lens based on the prescription as indicated by step 1420.The ophthalmic lens prescription may be configured to compensate for ameasured patient spherical aberration, compensate for a measured patientchromatic aberration, and provide an extended depth of focus. Relatedly,the lens may be configured to compensate for patient spherical andchromatic aberrations, and to provide an extended depth of focus. Insome cases, so as to provide the extended depth of focus, the lens mayprovide a far focus corresponding to a base power and an intermediatefocus corresponding to an add power, where a difference between the basepower and the add power defines an extended depth of focus for theophthalmic lens. In some cases, so as to provide the extended depth offocus, the lens may provide a modulation transfer function value at 50cycles per millimeter of at least 10, for an intermediate focus, at 3 mmand 5 mm pupil diameters.

FIG. 15 illustrates an exemplary system 1500 for generating anophthalmic lens prescription for an eye of a patient, according toembodiments of the present invention. The system includes an input 1510that accepts a patient parameter data profile specific for the patienteye. The patient parameter data profile may include a patient sphericalaberration parameter corresponding to a measured spherical aberration ofthe patient eye, and a patient chromatic aberration parametercorresponding to a measured chromatic aberration of the patient eye. Thesystem also includes a module 1520 having a tangible medium embodyingmachine-readable code that generates the ophthalmic lens prescriptionfor the eye. As shown here, the prescription is for a lens thatcompensates for the measured spherical and chromatic aberrations andthat provides an extended depth of focus. In some cases, so as toprovide the extended depth of focus, the lens may provide a far focuscorresponding to a base power and an intermediate focus corresponding toan add power, where a difference between the base power and the addpower defines an extended depth of focus for the ophthalmic lens. Insome cases, so as to provide the extended depth of focus, the lens mayprovide a modulation transfer function value at 50 cycles per millimeterof at least 10, for an intermediate focus, at 3 mm and 5 mm pupildiameters.

FIG. 16 depicts an exemplary system 1600 for fabricating an ophthalmiclens for an eye of a patient. The system includes an input 1610 thataccepts an ophthalmic lens prescription for the patient eye. Theprescription is for a lens that compensates for measured spherical andchromatic aberrations of the eye of the patient, and that provides anextended depth of focus to the eye of the patient. The system alsoincludes a manufacturing assembly 1620 in connectivity with the inputthat fabricates an ophthalmic lens according to the lens prescription.

Each of the calculations, operations, methods, and processes describedherein may be performed using a computer or other processor havinghardware, software, and/or firmware. The various method steps may beperformed by modules, and the modules may comprise any of a wide varietyof digital and/or analog data processing hardware and/or softwarearranged to perform the method steps described herein. The modulesoptionally comprising data processing hardware adapted to perform one ormore of these steps by having appropriate machine programming codeassociated therewith, the modules for two or more steps (or portions oftwo or more steps) being integrated into a single processor board orseparated into different processor boards in any of a wide variety ofintegrated and/or distributed processing architectures. These methodsand systems will often employ a tangible media embodyingmachine-readable code with instructions for performing the method stepsdescribed above. Suitable tangible media may comprise a memory(including a volatile memory and/or a non-volatile memory), a storagemedia (such as a magnetic recording on a floppy disk, a hard disk, atape, or the like; on an optical memory such as a CD, a CD-R/W, aCD-ROM, a DVD, or the like; or any other digital or analog storagemedia), or the like.

The embodiments described above, including accompanying drawings,figures, functions and tables, are for illustrative purposes to explainaspects of the present invention. Hence, while the exemplary embodimentshave been described in some detail, by way of example and for clarity ofunderstanding, those of skill in the art will recognize that a varietyof modification, adaptations, and changes may be employed. Hence, thescope of the claims should not be limited to the description of thepreferred versions contained herein.

What is claimed is:
 1. An ophthalmic lens, comprising: a first surfaceand a second surface, the first and second surfaces disposed about anoptical axis; an aspheric refractive profile imposed on the first orsecond surface; and a diffractive profile imposed on the first or secondsurface, wherein the aspheric refractive profile focuses light toward afar focus, and wherein the diffractive profile comprises a central zonethat distributes a first non-zero percentage of light toward a far focusand a second non-zero percentage of light toward an intermediate focus,and a peripheral zone, surrounding the central zone, that distributes athird non-zero percentage of light toward the far focus and a fourthnon-zero percentage of light toward the intermediate focus, wherein thepercentage of light distributed by the peripheral zone toward the farfocus is 63% and the percentage of light distributed by the peripheralzone toward the intermediate focus is 21%.
 2. The ophthalmic lensaccording to claim 1, wherein the intermediate focus corresponds to anadd power within a range between 1 Diopter and 2.5 Diopters.
 3. Theophthalmic lens according to claim 1, wherein the intermediate focuscorresponds to an add power between 0.75 and 2 Diopters.
 4. Theophthalmic lens according to claim 1, wherein the intermediate focuscorresponds to an add power of 1.75 Diopters.
 5. The ophthalmic lensaccording to claim 1, wherein the far focus corresponds to a firstdiffractive order of the diffractive profile.
 6. The ophthalmic lensaccording to claim 1, wherein the far focus corresponds to a seconddiffractive order of the diffractive profile.
 7. The ophthalmic lensaccording to claim 1, wherein the far focus corresponds to a thirddiffractive order of the diffractive profile.
 8. The ophthalmic lensaccording to claim 1, wherein a difference between the intermediatefocus and the far field focus corresponds to a power value within arange from about 1 Diopter to about 2.5 Diopters.
 9. The ophthalmic lensaccording to claim 1, wherein a difference between the intermediatefocus and the far field focus corresponds to a power of about 1.75Diopters.
 10. The ophthalmic lens according to claim 1, wherein thepercentage of light distributed by the central zone toward the far focusis within a range between 41% and 63%, and the percentage of lightdistributed by the central zone toward the intermediate focus is withina range between 21% and 41%.
 11. The ophthalmic lens according to claim1, wherein the percentage of light distributed by the central zonetoward the far focus is 41% and the percentage of light distributed bythe central zone toward the intermediate focus 41%.
 12. The ophthalmiclens according to claim 1, wherein the central zone comprises one ormore echelettes each having a step height, and wherein the peripheralzone comprises a plurality of echelettes each having a step height thatis less than the step height of each central zone echelette.
 13. Theophthalmic lens according to claim 12, wherein the central zonecomprises two or more echelettes.
 14. The ophthalmic lens according toclaim 12, wherein the central zone comprises two, three, or fourechelettes.
 15. An ophthalmic lens, comprising: a first surface and asecond surface, the first and second surfaces disposed about an opticalaxis; an aspheric refractive profile imposed on the first or secondsurface; and a diffractive profile imposed on the first or secondsurface, wherein the aspheric refractive profile focuses light toward afar focus, and wherein the diffractive profile comprises a central zonethat distributes a first non-zero percentage of light toward a far focusand a second non-zero percentage of light toward an intermediate focus,and a peripheral zone, surrounding the central zone, that distributes athird non-zero percentage of light toward the far focus and a fourthnon-zero percentage of light toward the intermediate focus, wherein thecentral zone comprises at least one echelette having a step height ofabout 0.006 millimeters, and wherein the peripheral zone comprises atleast one echelette having a step height of about 0.0055 millimeters.16. An ophthalmic lens, comprising: a first surface and a secondsurface, the first and second surfaces disposed about an optical axis;an aspheric refractive profile imposed on the first or second surface;and a diffractive profile imposed on the first or second surface,wherein the aspheric refractive profile focuses light toward a farfocus, and wherein the diffractive profile comprises a central zone thatdistributes a first non-zero percentage of light toward a far focus anda second non-zero percentage of light toward an intermediate focus, anda peripheral zone, surrounding the central zone, that distributes athird non-zero percentage of light toward the far focus and a fourthnon-zero percentage of light toward the intermediate focus, wherein thecentral zone comprises at least one echelette having an optical pathdifference of 1.5 wavelengths, and wherein the peripheral zone comprisesat least one echelette having an optical path difference of 1.366wavelengths.
 17. The ophthalmic lens according to claim 1, wherein thecentral zone comprises two echelettes each having a step height, and theperipheral zone comprises seven echelettes each having a step heightless than the step heights of the central zone echelettes.
 18. Anophthalmic lens, comprising: a first surface and a second surface, thefirst and second surfaces disposed about an optical axis; an asphericrefractive profile imposed on the first or second surface; and adiffractive profile imposed on the first or second surface, wherein theaspheric refractive profile focuses light toward a far focus, andwherein the diffractive profile comprises a central zone thatdistributes a first non-zero percentage of light toward a far focus anda second non-zero percentage of light toward an intermediate focus, anda peripheral zone, surrounding the central zone, that distributes athird non-zero percentage of light toward the far focus and a fourthnon-zero percentage of light toward the intermediate focus, wherein thecentral zone comprises an inner echelette having an outer diameter of1.6 mm and an outer echelette having an outer diameter of 2.2 mm,wherein the inner and outer echelettes of the central zone each have astep height, and wherein the peripheral zone comprises seven echeletteseach having a step height less than the step heights of the central zoneechelettes.
 19. An ophthalmic lens, comprising: a first surface and asecond surface, the first and second surfaces disposed about an opticalaxis; an aspheric refractive profile imposed on the first or secondsurface; and a diffractive profile imposed on the first or secondsurface, wherein the aspheric refractive profile focuses light toward afar focus, and wherein the diffractive profile comprises a central zonethat distributes a first non-zero percentage of light toward a far focusand a second non-zero percentage of light toward an intermediate focus,and a peripheral zone, surrounding the central zone, that distributes athird non-zero percentage of light toward the far focus and a fourthnon-zero percentage of light toward the intermediate focus, wherein thelens provides an MTF at 50 c/mm of 24 at the intermediate focus and anMTF at 50 c/mm of 44 at the far focus.
 20. The ophthalmic lens accordingto claim 15, wherein the intermediate focus corresponds to an add powerwithin a range between 1 Diopter and 2.5 Diopters.
 21. The ophthalmiclens according to claim 15, wherein the intermediate focus correspondsto an add power between 0.75 and 2 Diopters.
 22. The ophthalmic lensaccording to claim 15, wherein the intermediate focus corresponds to anadd power of 1.75 Diopters.
 23. The ophthalmic lens according to claim15, wherein the far focus corresponds to a first diffractive order ofthe diffractive profile.
 24. The ophthalmic lens according to claim 15,wherein the far focus corresponds to a second diffractive order of thediffractive profile.
 25. The ophthalmic lens according to claim 15,wherein the far focus corresponds to a third diffractive order of thediffractive profile.
 26. The ophthalmic lens according to claim 15,wherein a difference between the intermediate focus and the far fieldfocus corresponds to a power value within a range from about 1 Diopterto about 2.5 Diopters.
 27. The ophthalmic lens according to claim 15,wherein a difference between the intermediate focus and the far fieldfocus corresponds to a power of about 1.75 Diopters.
 28. The ophthalmiclens according to claim 15, wherein the central zone comprises two ormore echelettes.
 29. The ophthalmic lens according to claim 15, whereinthe central zone comprises two, three, or four echelettes.
 30. Theophthalmic lens according to claim 16, wherein the intermediate focuscorresponds to an add power within a range between 1 Diopter and 2.5Diopters.
 31. The ophthalmic lens according to claim 16, wherein theintermediate focus corresponds to an add power between 0.75 and 2Diopters.
 32. The ophthalmic lens according to claim 16, wherein theintermediate focus corresponds to an add power of 1.75 Diopters.
 33. Theophthalmic lens according to claim 16, wherein the far focus correspondsto a first diffractive order of the diffractive profile.
 34. Theophthalmic lens according to claim 16, wherein the far focus correspondsto a second diffractive order of the diffractive profile.
 35. Theophthalmic lens according to claim 16, wherein the far focus correspondsto a third diffractive order of the diffractive profile.
 36. Theophthalmic lens according to claim 16, wherein a difference between theintermediate focus and the far field focus corresponds to a power valuewithin a range from about 1 Diopter to about 2.5 Diopters.
 37. Theophthalmic lens according to claim 16, wherein a difference between theintermediate focus and the far field focus corresponds to a power ofabout 1.75 Diopters.
 38. The ophthalmic lens according to claim 16,wherein the central zone comprises two or more echelettes.
 39. Theophthalmic lens according to claim 16, wherein the central zonecomprises two, three, or four echelettes.
 40. The ophthalmic lensaccording to claim 18, wherein the far focus corresponds to a firstdiffractive order of the diffractive profile.
 41. The ophthalmic lensaccording to claim 18, wherein the far focus corresponds to a seconddiffractive order of the diffractive profile.
 42. The ophthalmic lensaccording to claim 18, wherein the far focus corresponds to a thirddiffractive order of the diffractive profile.
 43. The ophthalmic lensaccording to claim 18, wherein the percentage of light distributed bythe central zone toward the far focus is within a range between 41% and63%, and the percentage of light distributed by the central zone towardthe intermediate focus is within a range between 21% and 41%.
 44. Theophthalmic lens according to claim 18, wherein the percentage of lightdistributed by the central zone toward the far focus is 41% and thepercentage of light distributed by the central zone toward theintermediate focus 41%.
 45. The ophthalmic lens according to claim 18,wherein the percentage of light distributed by the peripheral zonetoward the far focus is 41% or more and the percentage of lightdistributed by the peripheral zone toward the intermediate focus is 41%or less.
 46. The ophthalmic lens according to claim 18, wherein thecentral zone comprises one or more echelettes each having a step height,and wherein the peripheral zone comprises a plurality of echelettes eachhaving a step height that is less than the step height of each centralzone echelette.
 47. The ophthalmic lens according to claim 18, whereinthe central zone comprises two or more echelettes.
 48. The ophthalmiclens according to claim 18, wherein the central zone comprises two,three, or four echelettes.
 49. The ophthalmic lens according to claim19, wherein the intermediate focus corresponds to an add power within arange between 1 Diopter and 2.5 Diopters.
 50. The ophthalmic lensaccording to claim 19, wherein the intermediate focus corresponds to anadd power between 0.75 and 2 Diopters.
 51. The ophthalmic lens accordingto claim 19, wherein the intermediate focus corresponds to an add powerof 1.75 Diopters.
 52. The ophthalmic lens according to claim 19, whereinthe far focus corresponds to a first diffractive order of thediffractive profile.
 53. The ophthalmic lens according to claim 19,wherein the far focus corresponds to a second diffractive order of thediffractive profile.
 54. The ophthalmic lens according to claim 19,wherein the far focus corresponds to a third diffractive order of thediffractive profile.
 55. The ophthalmic lens according to claim 19,wherein a difference between the intermediate focus and the far fieldfocus corresponds to a power value within a range from about 1 Diopterto about 2.5 Diopters.
 56. The ophthalmic lens according to claim 19,wherein a difference between the intermediate focus and the far fieldfocus corresponds to a power of about 1.75 Diopters.
 57. The ophthalmiclens according to claim 19, wherein the percentage of light distributedby the central zone toward the far focus is within a range between 41%and 63%, and the percentage of light distributed by the central zonetoward the intermediate focus is within a range between 21% and 41%. 58.The ophthalmic lens according to claim 19, wherein the percentage oflight distributed by the central zone toward the far focus is 41% andthe percentage of light distributed by the central zone toward theintermediate focus 41%.
 59. The ophthalmic lens according to claim 19,wherein the percentage of light distributed by the peripheral zonetoward the far focus is 41% or more and the percentage of lightdistributed by the peripheral zone toward the intermediate focus is 41%or less.
 60. The ophthalmic lens according to claim 19, wherein thecentral zone comprises one or more echelettes each having a step height,and wherein the peripheral zone comprises a plurality of echelettes eachhaving a step height that is less than the step height of each centralzone echelette.
 61. The ophthalmic lens according to claim 19, whereinthe central zone comprises two or more echelettes.
 62. The ophthalmiclens according to claim 19, wherein the central zone comprises two,three, or four echelettes.